Method of forming a tool assembly

ABSTRACT

A gang tool assembly for drilling a precise pattern of holes in a workpiece or otherwise cutting surfaces and the like on such workpiece and including a mounting panel of rigid sheet material having a pattern of holes formed therein to receive supports for powered tool heads to detachably support the same to form a gang pattern of either drills or cutters for simultaneously drilling a pattern of holes in a workpiece or forming a contoured surface thereon. The mounting panel is formed by at least pricking with pins a pattern of holes upon a sheet-like pattern of all holes to be drilled and forming partial patterns of the entire pattern separately upon said sheet-like pattern and digitizing the same upon a tape for use in a numerically controlled machine operable to successively drill a series of rigid sheet-like support plates for holding powered drill heads in partial patterns of said entire pattern and comprising a set thereof for use to drill patterns of holes in sets of test and base plates respectively requiring holes of different diameters for use in ultimately drilling holes in product sheet material having the entire required pattern of holes therein.

This is a division of application Ser. No. 231,340, filed Feb. 4, 1981.

BACKGROUND OF THE INVENTION

To a certain extent, the present invention was inspired by attempting tosolve the problem of drilling multiple holes in printed circuit boardswhich, even in small sizes, frequently have a very substantial number ofholes of varying diameters drilled in precise patterns therein forpurposes of receiving connecting pins, contacts or wires on variouselectrical components which are integrally fixed to the printed circuiton the board by soldering. Drilling such a multiplicity of holes hasheretofore been a very time-consuming operation, the crudest methodscomprising individually drilling said holes by a single drill mountedeither in a drill press or in a numerically controlled drilling machinehaving a limited number of variably movable drill heads. The closerelationship of said holes in such circuit boards renders the drillingthereof by automatic means very difficult in view of the need tosimultaneously operate a plurality of drills in a precise patternwithout conflict between the various drills which must be powered, andalso sometimes requiring the changing of drill bits to form a pluralityof diameters occasionally required.

It has been the practice in certain manufacturing operations to operatea multiplicity of drills by various power means where the closeproximity of the holes drilled thereby is not as acute as found in thedrilling of holes in printed circuit boards. For example, in drillingspaced holes in ladder rails for receiving the ends of the rungs of theladder by means of a gang of drills is well-known and providing powermeans to operate such drills simultaneously is readily solved by geartrains, chains, or otherwise. Further, gang drilling machines which haveadjustable mounts for the drills to accommodate the same to differentpatterns also are known, and examples of these are included among thefollowing patents, which are typical of mechanically-operated drillingmachines in which the drills are operated by gears or otherwise, asreferred to above:

U.S. Pat. No. 2,215,273 Paradis: Sept 17, 1940

U.S. Pat. No. 3,635,570 DeGelleke et al: Jan 18, 1972

U.S. Pat. No. 3,765,787 Hart et al: Oct. 16, 1973

U.S. Pat. No. 3,822,958 Lewis: July 9, 1974

U.S. Pat. No. 4,090,803 Haley: May 23, 1978

Another problem existing in the operation of gang drills comprisesdetecting either malfunctioning individual drills or broken drill bits,especially when mass production is involved, and efforts have been madeheretofore to provide various types of detecting means for such brokenbits or malfunctioning power means, and typical examples of such devicesare illustrated in the following patents:

U.S. Pat. No. 3,025,728 Cross et al: Mar. 20, 1962

U.S. Pat. No. 3,310,796 Sanders: Mar. 21, 1967

U.S. Pat. No. 3,381,550 Smith: May 7, 1968

U.S. Pat. No. 3,627,437 Smith: Dec. 14, 1941

U.S. Pat. No. 3,669,557 Mitchell: June 13, 1972

U.S. Pat. No. 3,747,085 Bala et al: July 17, 1973

Forming a support means for a multiplicity of drills also has been aproblem requiring attention heretofore but especially where theproximity of the holes to be drilled is not acute, compared to drillingof holes in printed circuit boards, it has not been particularlydifficult to devise supports and mounting means for a plurality of drillshanks or chucks, but especially where drill holes are in very closeproximity, as in printed circuit boards, some means for forming asupport for a plurality of preferably small size power heads has givenrise to the investigation of employing suitable means and methods forforming such support means of rigid sheet-like type and investigationsof suitable solutions for providing such support means comprises thesubject matter of the present invention. In this, as described ingreater detail hereinafter, the basic support plate is formed bydrilling in a set of similar sizes and shapes of rigid sheet material,such as metal or plastic, partial patterns of holes comprising parts ofa complete pattern of holes to provide support for powered drill headspositioned on said plates in a manner not to conflict with each otherand operable successively upon product sheet material to form a desiredcomplete pattern of holes therein.

SUMMARY OF THE INVENTION

It is among the principle objects of the present invention to provide agang drill assembly for drilling a precise pattern of holes in productsheet of material in which the holes may be of various diameters andalso very closely spaced from each other, one typical commercial exampleof which comprises printed circuit boards. Said assembly includes a setof rigid support plates in which partial patterns of an entire patternof holes are formed respectively to receive supports for powered drillheads to detachably support the same and thereby form a gang pattern ofcutting drills for simultaneously drilling a desired complete pattern ofholes in product sheet material, such as, for example, printed circuitboards.

Another object of the invention is to form said set of support plates byusing a diagram or pattern sheet on which the entire pattern of holes isshown and either pricking or inserting in selected holes of said patternplugs having sharp points and heads, the heads being substantially equalin diameter to powered drill heads to be attached to said supportplates, and recording the positions of said pricks or plugs upon a tapefor use in a numerically-controlled drilling machine to drill an entireset by such recordings respectively in a set of rigid support plates andadditional base and inspection plates respectively for supporting andtesting drilled product sheets of material formed by using said set ofsupport plates with drill heads attached thereto as gang drillassemblies, ultimately to form a complete identical pattern of holes insaid product sheets.

A further object of the invention is to provide between the operation ofeach gang drill assembly of said aforementioned set thereof, detectingprobes or the like, arranged in a pattern identical with that of thepattern of drills on said gang drill assembly with which it isassociated in operation so that by inserting said probes in the drilledholes, any holes which have not been properly drilled readily will bedetected and appropriate signal means actuated to call attention to suchimproper drilling, such as resulting from a broken drill bit or thelike.

Still another object of the invention is to provide detecting means fora malfunctioning power unit which, for example, though not restrictedthereto, may respond to sound, and such detecting means individually areassociated with each power head and connected in circuit with audibleand/or visible indicating means to call attention to such malfunctioningof the power head.

A still further object of the invention is to provide a system wherebysaid set of gang drill assemblies interspersed with detecting means maybe used to completely drill all required holes in a product sheet ofmaterial, such as described hereinabove.

Still another object of the invention is to arrange a gang drillassembly in which a pattern of drills and power heads are arranged toperform other functions than merely drilling holes, such as by operatingin unison in a certain pattern to function in a planing or millingoperation and/or in a circular pattern for cutting annular grooves orcutting discs from a sheet of material, and otherwise.

Details of the foregoing objects and of the invention, as well as otherobjects thereof, are set forth in the following specification andillustrated in the accompanying drawings comprising a part thereof.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a plan view of a typical printed circuit board in which aplurality of holes are shown in elements of the circuit illustratedthereon.

FIG. 2 is a perspective view of an exemplary set of printed circuitboards mounted upon a base plate in flately stacked manner with respectto aligning pins.

FIG. 3 is a fragmentary section of an exemplary rigid support plate madein accordance with the invention and showing respectively, in sectionalmanner, a pressure element reciprocably mounted therein, and a powereddrill head supported by a shaft mounted in an opening in said supportplate.

FIG. 4 is a vertical sectional view of indicating mechanism fordetecting improperly drilled holes in a stack of printed circuit boards,and also showing exemplary indicating means.

FIG. 5 is a vertical sectional view of a powered drill head embodying afluid-operated turbine connected to a supporting shaft mounted in asheet of material or support means as a panel shown in FIG. 3.

FIG. 6 is a horizontal sectional view of the powered drill head shown inFIG. 5, as seen on the line 6--6 thereof.

FIG. 7 is a diagram showing indicating and detecting means for amalfunctioning drill head.

FIG. 8 is a fragmentary diagrammatic plan view showing a pattern ofdrill heads mounted for a milling or planing operation.

FIG. 9 is a diagrammatic pattern of a circular arrangement of drillheads adapted to be moved about an axis to effect a circular cut in aworkpiece.

FIGS. 10, 11 and 12 show side elevations of different types of plugs andpoints thereon used in relation to the invention.

FIGS. 13 and 14 respectively show exemplary drill head patterns in arelated pair of panels of a set thereof adapted to be successivelyoperated upon a stack of printed circuit boards incident to completelydrilling a desired pattern of holes therein.

FIG. 15 is a vertical elevation showing a machine system for drillingholes in electronic printed circuit boards and embodying a series ofsuccessively operated gang drill assemblies, each respectively drillinga partial pattern of holes comprising a portion of an overall pattern ofholes to be drilled in sets of printed circuit boards and also includingmeans to detect and signal incompletely drilled holes and additionalmeans to detect and indicate malfunctioning drill heads.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As indicated above, development of the present invention was at leastpartially inspired by attempting to solve the problem of drilling holesin a printed circuit board but the invention is not to be restrictedsimply to this function since a multiplicity of drill heads, havingcutting bits therein, and made in accordance with the present invention,have application in other operations and functions described in detailhereinafter.

Referring to FIG. 1, a typical plan view of a printed circuit board isshown in which a sheet of stiff insulating board material 10 is shownupon which a pattern of an electric circuit of "printed" metal 12 isshown in black and being representative of one type of product sheetmaterial adapted to be formed by the present invention. By processes notinvolved in the present invention, the metallic electric circuit ofprinted circuit boards is applied to the insulating board 10 and firmlyadheres thereto. The board also has a multiplicity of holes 14 of smalldiameter drilled therein in the center of enlarged metallic areasforming an integral part of the electrical circuit and to which variouswire-type leads or contacts of different types of electrical componentsare connected by extending through said holes and then being integrallyattached to the circuit 12 by means of solder.

For purposes of orienting individual circuit boards or other sheet typeproducts incident to drilling, for example, a limited number thereofsimultaneously by means embodying the present invention, as described indetail hereinafter, each board or product is also provided withpositioning holes 16, which are identical in each one. Referring to FIG.2, there is illustrated therein a holding or base plate 18 for use in anoverall machine system, described hereinafter, which is utilized tosupport a plurality of the exemplary boards 10 in stacked relationshipupon guide and positioning pins 20, which are rigidly connected to andextend upward from the top surface of plate 18 to project through theholes 16 in the circuit boards 10.

As also referred to hereinabove, one of the principal objects of thepresent invention is to form a very rigid supporting panel for aplurality of drill heads and/or testing heads or the like, said panelpreferably being formed from sheet metal or plastic material of suitablethickness to remain rigid in use to support powered drill heads and thelike.

Referring to FIG. 3, there is illustrated therein, typical devicessupported by the rigid support plate 22, which is shown fragmentarilyand preferably is of uniform thickness of sheet metal or plasticmaterial. In the left-hand portion of plate 22, there is illustrated ashaft slidable in a bearing hole in the plate comprising a pressuremember 24 having a presser foot on the lower end and a movement-limitingadjustable nut 28 on the upper end. A compressible spring 30 surroundsshaft 24 between the lower surface of support plate 22 and presser foot26, whereby when drill bits or test probes, described in detailhereinafter, are withdrawn from the sheet-like product circuit boards10, the presser feet 26 engage either a single or the uppermost of astack of product boards 10 to hold the same against base plates 18 andthereby not disturb the same relative to positioning pins 20. Feet 26also hold plates 10 flat while being drilled.

One of the highly important devices to be supported respectively bysupporting shafts 32 comprise powered drill heads 34. Said shafts extendthrough holes of a partial pattern of the entire desired pattern ofholes to be drilled in boards 10 and are provided with a flange 36 whichabuts the lower surface of support plate 22, and suitable means, such asa nut 38, clamp the shafts to the plate 22. A powered drill head 34 isfirmly connected to the lower end of the shaft 32, which, as will bedescribed hereinafter, is one of a number thereof attached to eachsupport plate 22 of a set thereof respectively having a partial patternof powered drill heads 34 thereon adapted sequentially to drill a fulldesired pattern of holes in the product boards 10.

It also is to be understood that, in accordance with the presentinvention, there are detecting heads 46 mounted on separate supportplates 44, one of which is shown in FIG. 4, which is different from thatwhich supports the drill heads 40 but the patterns of the holes in therespective panels in which they are mounted are the same for purposesrespectively of sequentially drilling a desired pattern of holes inproduct sheets of material, such as the printed circuit boards 10 and,immediately thereafter, checking the drilled holes to determine thecompleteness of said drilling or the existence of one or more broken orloose drill bits or the like, which situation is detected by the probes48, for example.

Although other types of powered drill heads than the one specificallyillustrated in FIGS. 5 and 6 may be employed to effect gang drilling ofa pattern of holes in a product sheet of material, such as a printedcircuit board, it is essential that for purposes of space economy informing a given set of gang drill assemblies and corresponding detectingassemblies, that as many drill heads as possible be mounted withoutconflict with each other on any individual gang drilling assembly of aset thereof. For this purpose, it is preferred that the powered drillheads be of miniature nature, especially where the holes 14 in aspecific pattern thereof in a product, such as a circuit board 10, arearranged in very close proximity.

In view of the foregoing, the type of power head selected preferably fordrilling holes in accordance with the principles of the presentinvention, comprises an air-driven turbine 56 of minature type,rotatably supported by anti-friction bearings within a cylindricalhousing 58. For more complete details of the type of drill head which ispreferred, attention is directed to prior U.S. Pat. No. 3,077,333 toGotwald et al., dated Feb. 12, 1963. The fluid for operating the turbineis preferably air or other convenient type of gas delivered underpressure through a lateral neck 60 which terminates in a connectingnozzle 62 to which a suitable, preferably flexible, air conduit isconnected and the opposite end thereof is connected to a suitable sourceof air under pressure, not shown.

As shown in FIG. 6, the neck 60 is provided with an air inlet port 64,which extends outwardly through the nozzle 62 and an exhaust port 66 isalso formed in the neck 60 for immediate discharge of spent air from theturbine 56. The shaft of turbine 56 contains an appropriate chuck 68,which supports a cutting bit or drill 70, as clearly shown in FIG. 5.

The shafts 32 for supporting the drill heads 34 are shown in greaterdetail and in larger scale in FIG. 5, than otherwise shown in FIG. 3,and it will be seen that the shafts 32 terminate at the lower endthereof in an annular shoulder 72, which abuts the lower surface of thesupport plates 22 when assemblying the required quota of drill headsupon said plate and the upper ends of the shafts 32 are threaded toreceive the nuts 74 and thereby firmly secure the shafts 32 to thesupport plates 22. If desired, shafts 32 may be tubular and therebyafford an additional air exhaust passage to accommodate air dischargedfrom the vanes of the turbine 56 through the upper anti-friction bearing76 for purposes of lubricating and/or cooling the same during operation.Similarly, there is clearance in the bottom wall of the housing 58through which the lower end of the turbine shaft extends to permit thedischarge of air therethrough after it has passed through the loweranti-friction bearing 78.

Referring to FIGS. 13 and 14, there is illustrated two exemplarydifferent support plates 22a and 22b, comprising parts of a complete setof coordinated patterns which supplement each other so that in theaggregate, after each of the support plates with the pattern of powereddrill heads mounted thereon have completed drilling, for example, alimited stack of identical products, such as printed circuit boards, allof the holes in said boards of a complete pattern thereof, will havebeen drilled. As shown in FIGS. 13 and 14, the exemplary pattern ofholes 14 is shown in the form of tiny circles that represent most of theentire number of holes shown in the board 10 in FIG. 1, suchillustrations comprise an arrangement of circles representingdiagrammatically illustrated drill heads 34 in which none of themconflict with each other, and therefore, are capable of being mounted inindividual cooperative patterns respectively in the support plates 22 ofa complete set thereof. Accordingly, by orienting all of the patterns ofdrill heads 34 with respect to the positioning holes 16, which, in turn,also orient a stack of the product printed circuit boards 10 withrespect to the positioning pins 20, as shown in FIG. 1, it is possibleto accurately drill an entire complement of holes in a printed circuitboard having a desired pattern of holes to be formed therein. Holes 45are formed to receive attaching bolts or the like to secure devices,such as supporting brackets, to the support plates 22.

Another consideration to be observed is that, in view of the fact thatthe preferred type of powdered drill heads 34 are of the air turbinetype, space must be provided for connecting air or gas delivery hoses tothe neck 60 of each drill head 34, and it can be visualized from thepattern of drill heads in FIGS. 13 and 14 that such arrangement ispossible.

Attention is now directed to FIG. 15, in which there is illustrated anexemplary machine system for utilizing each of the individual gang drillassemblies 80, 82, 84 and 86, comprising an exemplary set thereof,adequate to completely drill all of the required holes in a specificexample of sheet product, such as printed circuit boards. Saidassemblies respectively include individual support plates 22, eachhaving a given complement of a partial pattern of drill heads 34 mountedthereon in cooperative patterns jointly and sequentially capable ofproviding the full complement of holes to be drilled in stacks 88 ofblank product printed circuit boards 10, the exemplary stack thereofnearest the left-hand end of FIG. 15 being completely undrilled. Anendless conveyor 90 extends around a pair of rotatable supporting drums92 and 94, one of which is driven by a suitable source of power, notshown, in stepwise manner, sequentially to advance the stacks 88 of thecircuit boards respectively to the gang drill assemblies and also to theintermediate testing head assemblies 96, 98, 100 and 102, which, likethe gang drill assemblies 80-86, are commonly attached to the lowersurface of a reciprocatory frame 104, clearly illustrated in FIG. 15.

The testing head assemblies 96-102 each preferably comprise a supportplate 44 which are similar to plates 22, illustrated with respect to thegang drill assemblies 80-86, but may be thicker, if desired. As stated,the conveyor 90 is advanced stepwise to successively introduce to saidgang drill assemblies each of the base plates 18, which are detachablyconnected accurately to each equally spaced links of the endlessflexible conveyor 90, as clearly shown in FIG. 15. By suitable controlmeans for operating the motor which advances the conveyor 90, such as byrotation of the drum 94 in the direction of the arrows shown thereon,each of the stacks 88 of circuit boards are very accurately positionedsuccessively for vertical reciprocation of frame 104 that carries all ofthe gang drill assemblies 80-86 and testing head assemblies 96-102 sothat when the stacks 88 of circuit boards emerge at the right-hand endof the path traversed thereby, as shown in FIG. 15, any suitable meansmay be employed to remove the completely drilled stack 88 successivelyfrom the holding or base plates 18.

A number of commercially available, automatically controlled devices arecapable of reciprocating the frame 104, one well-known commercialexample of which comprises lead screws, a complement of ballnuts, astepping motor and the like, manufactured and sold by Warner ElectricBrake and Clutch Co., and capable of being operated in controlled mannerfor reciprocation of the frame 104 in a desired cycle of adequatevertical movements within a suitable time schedule. For example, theframe 104 may be reciporcated stepwise and successively retracted aftereach step, having in mind that in view of the very small diameter ofholes usually employed in printed circuit boards, the drills employed toform such holes are highly susceptible to breakage if applied steadilyin drilling manner to a workpiece for any sustained periof of time.Therefore, by reciprocating each gang drill assembly in successive stepsin which each step drills, for example, only a single circuit board, itcan be seen that if a stack of four circuit boards are to be drilled,four reciprocations of the drill assembly are made, each step descendingan additional amount equivalent to the thickness of a circuit board,until all of the circuit boards have been drilled.

In FIG. 15, exemplary actuating means 106 is illustrated to symbolizesuitable means to reciprocate the frame 104, either of the exemplarytype described above, or any other actuating mechanism, which preferablywill provide a step-type reciprocation for purposes of minimizingbreakage of drill bits or milling cutters, said reciprocation beingindicated by suitable arrows in the upper portion of FIG. 15.

TESTING MECHANISM

Especially in view of the fact that drilling holes of a small diameterin workpieces, such as printed circuit boards or otherwise, involves theuse of very small diameter drill bits, breakage of the same is notuncommon. The stepwise reciprocation thereof referred to above tends tominimize such breakage. However, especially in mass production ofdrilled printed circuit boards, which is one type of sheet product,contemplated for production by the exemplary equipment and systemillustrated in FIG. 15, it is preferred and actually is essential thattesting of the drilled workpieces be performed in a manner automaticallyto indicate the existence of incompletely drilled holes, for example,which usually will indicate the existence of a loose or broken drillbit, whereupon the operation of the machine may be stopped and thebroken bit can be replaced, after which operation of the machine iscontinued.

One exemplary form of testing equipment for use with a stack of productsof sheet material of which printed circuit boards are an example,comprises short shafts or heads 46, exemplary illustrations of which areincluded in FIG. 4, said shafts or heads being mounted for limitedreciprocation relative to support plate 44 and each supporting a probe48, for example, of an appropriate diameter to easily descend withinholes drilled in the stacks 88 of circuit boards 10, for example. InFIG. 4, there also is illustrated a vertically sectioned exemplaryassembly, showing a base plate 18 upon which a stack 88 of drilledcircuit boards is supported in conjunction with one of the testing headassemblies 96-102. The support plate 44 supports a complement of shortshafts or detecting heads 46 arranged in a partial pattern correspondingto such partial patterns of holes 14 in support plates 22 and eachpartial pattern is identical with a corresponding partial pattern ofdrill heads immediately upstream from the exemplary testing headassembly 96-102, shown in FIG. 4.

An exemplary drill bit fragment 108 is illustrated in one of the holesdrilled in the stack 88 of exemplary circuit boards, said fragment beingdisposed in one of the shallow holes 109 provided in the holding plate18 in order that the drill bit 70 may drill entirely through the stack88. The set up for drilling the holes by a numerically controlledmachine in the support plates 22, for example, to accommodate the shafts24 and 32, also may be used to drill the shallow holes 109 but usingsmaller diameter drill bits than for drilling the holes for shafts 24and 32. The fragment 108 extends up into at least the lowermost circuitboard in the stack 88, by way of example, whereby when the probe 48engages the fragment 108, it will raise the detecting head 46, asillustrated in exemplary manner in FIG. 4.

Preferably, the detecting heads 46 are metallic and the support plate 44also is metallic, as shown in FIG. 4. Support plate 44 is insulated fromthe testing head assemblies 96-102 by an electrical insulating frame110, which supports the support plate 44 and is secured to said testinghead assemblies 96-102 by any suitable means, such as screws 112. Ametallic contact sheet 114 extends along the lower interior surface ofinsulating frame 110. Exemplary indicating means in the form of anelectric lamp bulb 116 is supported in circuit with an exemplaryelectrical source 118, said circuit also respectively being connected inseries with contact sheet 114 and the metallic support plate 44 asillustrated adjacent the right-hand end of the illustration shown inFIG. 4. When the displaced detecting head 46 engages the contact sheet114, the bulb 116 will be lighted to constitute a signal that a brokendrill bit exists. Other forms of signals, visual or audible, may beused.

If desired, a more elaborate detecting system may be provided, asexplained hereinafter, so that in addition to merely indicating theexistence of a broken drill bit, the location of such drill bit in thepattern thereof, also may be indicated.

Referring to FIG. 7, there is illustrated therein a signal board 120,which includes a plurality of minute signal lights, for example,associated with numerical indicia to indicate the location of amalfunctioning drill head 34, one of which is shown in FIG. 7, supportedon the lower end of its mounting shaft 32, which, it will be understood,is supported in one of the support plates 22. A sound-responsivetransducer 122, such as the type used in phonograph pickup heads, forexample, is mounted on the upper end of each of the shafts 32, so as tobe responsive to sound generated by drill heads 34.

When, for example, the bearing 76 or 78 of one of the air turbine-typedrill heads 34 becomes worn beyond a desirable limit, a modified soundwill be produced by such a drill head and the transducer 122 is of thetype which will be responsive to such modified sound and transmit thesame to an amplifier 124, which is connected in circuit with a powersupply 126, for purposes of transmitting current to an individual signallight in the signal board 120, corresponding to the malfunctioning drillhead 34, it being understood that there is a circuit between eachtransducer and its corresponding signal light in the signal board 120. Acluster 128 of conducting wires, illustrated in exemplary manner in FIG.15, extends between the drill heads 34 of each gang drill assembly80-86, and the respective signal lights therefor in the signal board120, thereby visually and quickly indicating the existence of amalfunctioning drill head in order that service personnel may replacethe same.

Referring to FIGS. 8 and 9, additional types of operation embodyingpatterns of powered drill heads are illustrated therein. For example, inFIG. 8, by providing a head 130, supported by suitable mechanism, suchas a milling machine or the like, it is possible to mount a diagonal row132 of drill heads 34 thereon, and move the head 130 either in onedirection or reciprocate the same in opposite directions, as indicatedby the arrow shown in said figure. For purposes of having cutting bits,such as end mills, rotated by said row of drill heads to effect aplaning operation upon a flat workpiece 134, for example, it will beunderstood that the row 132 of drill heads can be at such an angle withrespect to the direction of movement of the head 130 that the cuttingends of all of the end mills will be in a common plane and willsupplement each other to make a complete cut across the width of theworkpiece 134, for example, similar to that of a planing machine orotherwise, especially if only a light cut is to be made.

As shown in FIG. 9, a circular head 136 may be provided with a circularpattern of drill heads to support a plurality of end mills 138, forexample, the cutting ends of which are all disposed in a common plane,and by rotating the heads 136, either in a single direction orreciprocating the same in opposite circular directions, the end millsare capable of cutting either a circular groove 140, shown in dottedlines in FIG. 9, or particularly in working with sheet material, sucharrangement may be employed to cut holes in or discs from a workpiecesheet. Therefore, the exemplary illustrations in FIGS. 8 and 9 serve toillustrate the versatility of such an arrangement of drill headspreferably supported by mounting heads and the like, illustrated inexemplary manner in FIGS. 8 and 9, to perform operations other thanmerely drilling holes in workpieces and in which, preferably, thesupporting heads are formed in a manner described above with respect toforming the support plates 22 for operation with the exemplary machinesystem illustrated in FIG. 16. For such operations, either the supportfor the drill heads may be moved relative to the workpiece or viceversa.

HOLE DRILLING OF SUPPORT PLATES

The partial patterns of holes formed in accordance with the invention inthe various plates and the like, such as base plates 18, support plates22 for holding drill heads 34, and support plates 44 for the detectingheads 46, conveniently may be produced by the use of single ormulti-spindle numerically-controlled drilling machines using aperforated tape. A suitable procedure to form such tapes and,thereafter, the various plates referred to above is as follows:

A pattern sheet of paper or otherwise upon which is printed orphotographed a pattern of holes to be produced in the finished productsheets 10 is used as a basis to select and produce the various partialpatterns respectively produced on such plates to form a complete setthereof. This sheet may be a drawing of a printed electrical circuit ofa printed circuit board in which a complete pattern of drilled holes areto be produced. The holes, for example, may be illustrated either asdots or small circles. An exemplary type of pattern of such exemplaryprinted circuit is illustrated in FIG. 1, in which the pattern 12 isshown, as described hereinabove. Such printed sheet is placed upon asuitable sheet of non-metallic material, for example, and sufficientlyyeildable to be susceptible to being penetrated by sharp objects.Plywood is highly suitable, but other forms of woods, bonded fibermaterial of which one type is sold under the trademark "Cellotex," orany other type of building material or the like, having suchcharacteristics may be used. The small circular holes 14 of the patternshown in FIG. 1 represent holes into which certain contacts orcomponents of electrical elements are to be inserted in the finishedprinted circuit board and assembly. In accordance with this aspect ofthe invention, it is contemplated that a plurality of plug-like members148 made of metal, plastic material, or any other appropriate substance,are illustrated in various types respectively in FIGS. 10-12 and have adiameter no less than that of the powered drill heads 34. In FIG. 12,the plug-like member 150 is different in shape and contour from themembers 148, shown respectively in FIGS. 10 and 11, for purposesdescribed hereinafter.

The plug-like members 148 and 150 each have an appendage extendingaxially from one end thereof. The various embodiments of plugs shown inFIGS. 10-12 have appendages of alternate types in which, in FIGS. 10 and12, the appendage 152 preferably is a relatively slim needle-like membersomewhat resembling a phonograph needle and is readily capable ofpenetrating through a selected circular configuration 146 of the printedcircuit pattern 12. By application of reasonable force, the appendagepenetrates the exemplary non-metallic sheet described, which is of ayieldable nature. Such penetration preferably is for the full extent ofthe appendage 152 in order to firmly position the plug-like member 148upon the upper surface of the yieldable sheet and the plug abuts thepattern on the paper sheet or photograph thereof.

It will be understood that in accordance with the foregoing description,especially pertaining to FIGS. 13 and 14, which are of exemplary nature,that a plurality of the plugs 148 will be applied to the pattern sheetand yieldable supporting sheet by impinging the same through thecircular configurations 146 in such an arrangement that the plugs do notinterfere with each other. As a result of this, when drill heads 34 aremounted upon the support plates 22, for example, there will besufficient clearance on the plate between the heads to accommodate asubstantial number of the heads comprising a partial pattern of theentire pattern of holes to be drilled.

After a full complement of one selected partial pattern of plug-likemembers 148 of the entire pattern of holes has been placed upon thepattern sheet, the plugs are removed and the holes formed in the patternsheet then are digitized by a scanning head of a conventionaltape-forming machine for use with a numerically controlled, spindle-typeautomatic drilling machine to form a duplicate pattern of holes, forexample, in the base plates 18 and support plates 22 and 44, it beingunderstood that the drilling machine will be fitted with drill bits ofappropriate diameter to form the desired diameter of holes in suchplates.

In the various embodiments of plug-like members illustrated in FIGS.10-12, the appendage 156 on plug 148 in FIG. 11 is tapered and threadedand the plug 148 preferably is knurled or roughened to facilitatemanipulating the threaded point into the yieldable sheet beneath thepattern sheet, for example.

The foregoing procedure is used to make a full set of partial patternsof holes to be drilled and digitizing them successively upon one or moretapes in a conventional tape producing machine. Two exemplary partialpatterns of holes are shown in FIGS. 13 and 14 by placing suitable plugsof the types shown in FIGS. 10-12 on the paper patterns to provideclearance for the drill heads 34, for example, on the support plates 22when drilled to receive the supporting shafts 32. Then, by using theperforated tapes formed for a complete set of partial patterns of theentire pattern, complete sets respectively of base plates 18 withclearance holes therein of suitable diameter; support plates 22 with theholes for shafts 24 and 32 therein, and test equipment support plates 44with the holes therein to support detecting heads therein, may beproduced automatically from the same tapes and the sets of such supportplates with the equipment mounted therein then may be mounted upon theconveyor 90 and reciprocating frame 104 to produce product sheets ofmaterial, such as printed circuit boards 10, or otherwise, at far lesscost then by systems and processes now used commercially andindustrially.

This application is companion to a somewhat related invention comprisingthe subject matter of U.S. patent application, Ser. No. 444,672, filedon even date herewith.

The foregoing description illustrates preferred embodiments of theinvention. However, concepts employed may, based upon such description,be employed in other embodiments without departing from the scope of theinvention. Accordingly, the following claims are intended to protect theinvention broadly, as well as in the specific forms shown herein.

We claim:
 1. A method of drilling or cutting a predetermined pattern ofholes or cuts in a product sheet of material comprising the steps of:(a)selecting from a diagram sheet of an entire pattern of holes to bedrilled in said product sheet of material desired partial patterns ofholes of said entire pattern of holes to be drilled therein, (b)digitizing said partial pattern of holes upon a tape for a numericallycontrolled drilling machine, (c) operating a numerically controlleddrilling machine as controlled by said digitized tape to drill saidpartial pattern of holes of predetermined diameter in a rigid sheet ofmaterial to form a rigid support plate having said partial pattern ofholes for supporting respectively therein powered tool heads, (d)successively forming additional complementary digitized partial patternsof holes in related and complementary tape recordals, (e) successivelyforming related and complementary partial patterns of holes inadditional rigid support plates to provide a set of said platescollectively embracing all holes to be drilled in said rigid supportplates, (f) mounting powered tool heads respectively in the holes insaid set of rigid support plates to form gang tool assemblies, and (g)drilling using said set of gang tools said partial patterns of holessuccessively in one or a stack of limited number of product sheets ofmaterial to achieve the entire desired pattern of holes therein.
 2. Themethod according to claim 1 in which the powered tool heads are of apredetermined diameter larger than the holes to be drilled thereby insaid similar product sheets and selection of said partial pattern ofholes in each support plate of said set thereof includes the furtherstep of arranging for accommodation of said powered tool heads on eachsupport plate of said set thereof by placing upon an entire pattern ofholes a plurality of similar pin-like members with heads equal indiameter to said powered tool heads in such manner that said heads ofsaid pin-like members do not overlap and pricks made in said patternindicate which of the holes to be drilled have been selected to form apartial pattern of hole indications for each individual support plate,and digitizing on a tape the location of each hole pricked by saidpin-like members respectively for each support plate of said set thereofto be formed to support said powered tool heads.
 3. The method accordingto claim 2 including the further steps of utilizing said sets of supportplates with powered tool heads mounted thereon sequentially to drill ina set of base plates for one or more similar stacked product sheets ofmaterial a set of holes corresponding respectively to the partialpattern of the entire pattern of holes for said similar product sheetsand drilling said holes to a depth sufficient to accommodate the tipportions of test probes arranged in a partial pattern correspondingrespectively to each support plate for said entire set thereof.
 4. Themethod according to claim 3 including the further step of utilizing saidsets of support plates with powered tool heads mounted therein to drillin a further set of testing support plates a set of holes for testprobes having heads of larger diameter than the probes, said set ofholes being the size of the holes for said similar product sheets, andutilizing said sets of holes in said another set of support plates asguide holes for individually drilling holes of larger diameter thereinto accommodate said larger diameter heads of said probes forreciprocable testing movements.
 5. The method according to claim 3including the further step of providing said base plates with a limitednumber of positioning pins in strategic locations not interfering withthe pattern of holes to be drilled in said circuit boards, and initiallyforming in said similar product sheets identical patterns of positioningholes of the same diameter as said guide pins and corresponding in exactlocation to said pattern of guide pins.
 6. The method according to claim1 including the further step of mounting upon each support plate of saidset thereof for powered tool heads a limited number of spring pressedplungers having presser feet extending toward the similar product sheetsto be drilled and located on said support plates in areas notinterfering with said tool heads.